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Phase stability for the Cu–Zr system / S.H. Zhou in Acta materialia, Vol. 58 N° 6 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2186–2196 Titre : Phase stability for the Cu–Zr system : First-principles, experiments and solution-based modeling Type de document : texte imprimé Auteurs : S.H. Zhou, Auteur ; R.E. Napolitano, Auteur Année de publication : 2011 Article en page(s) : pp. 2186–2196 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Copper  alloys  Intermetallic  compounds  Thermodynamics  Phase  transformations Résumé : First-principles calculations and experimental methods were employed to investigate the relative stability of intermetallic phases in the Cu–Zr system. Computed enthalpies of formation indicate that Cu51Zr14-β and CuZr2-C11b are stable phases, while Cu5Zr-C15b, Cu10Zr7-ϕ and CuZr-B2 are metastable at 0 K. Heat treatment and microanalysis revealed two important findings which clarify the phase equilibria. First, the stability range for the Cu5Zr-C15b phase was found to have a lower bound associated with an eutectoid invariant between 802 and 955 K, below which it decomposes to face-centered cubic Cu plus Cu51Zr14-β. Second, the Cu5Zr8 phase, previously reported as stable, was not observed in a Cu–56.4 at.% Zr alloy after holding at 955 and 1036 K for >100 h. This phase, therefore, was not considered to be stable. Based on computational and experimental results, Gibbs free energies were modeled, including the Cu2Zr-σ, Cu24Zr13-μ and metastable CuZr-(B19′ and B33) phases. The associated phase diagrams are presented. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008386 [article] Phase stability for the Cu–Zr system : First-principles, experiments and solution-based modeling [texte imprimé] / S.H. Zhou, Auteur ; R.E. Napolitano, Auteur . - 2011 . - pp. 2186–2196. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2186–2196 Mots-clés : Copper  alloys  Intermetallic  compounds  Thermodynamics  Phase  transformations Résumé : First-principles calculations and experimental methods were employed to investigate the relative stability of intermetallic phases in the Cu–Zr system. Computed enthalpies of formation indicate that Cu51Zr14-β and CuZr2-C11b are stable phases, while Cu5Zr-C15b, Cu10Zr7-ϕ and CuZr-B2 are metastable at 0 K. Heat treatment and microanalysis revealed two important findings which clarify the phase equilibria. First, the stability range for the Cu5Zr-C15b phase was found to have a lower bound associated with an eutectoid invariant between 802 and 955 K, below which it decomposes to face-centered cubic Cu plus Cu51Zr14-β. Second, the Cu5Zr8 phase, previously reported as stable, was not observed in a Cu–56.4 at.% Zr alloy after holding at 955 and 1036 K for >100 h. This phase, therefore, was not considered to be stable. Based on computational and experimental results, Gibbs free energies were modeled, including the Cu2Zr-σ, Cu24Zr13-μ and metastable CuZr-(B19′ and B33) phases. The associated phase diagrams are presented. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008386